This invention relates to apparatus for operating pneumatic switches, commonly referred to as air switches.
xe2x80x9cair switchxe2x80x9d is the name generally used to refer to devices that are actuated by delivery of a pulse of relatively high pressure air. Air switch assemblies usually comprise an electric switch, usually a diaphragm type switch. In use, the pulse of high pressure air, when incident upon a diaphragm, causes movement of the diaphragm which in turn causes the engagement or disengagement of electrical contacts to open or close an electric circuit.
Air switches are commonly used in installations such as spa baths or spa pools to operate pumps. They may also be used in a variety of other applications, for example for the operation of waste disposers in or adjacent to household kitchen areas. The main reason for use of air switches is to provide electrical safety. The delivery of a pulse of air to a remote location where electric contacts are located, minimises the risk of inadvertent electrocution of a user.
Known air switch operators work on a bellows system. Therefore, they typically include a push button mounted in a housing, with the flexible bellows provided between the button and an end of the housing. An air inlet/outlet port is usually provided at the end of the housing. When a user presses on the push button, the bellows usually compress in a concertina-like fashion to expel air out of the inlet/outlet port under pressure. Some form of biasing means, for example a spring, is provided to return the button to the initial position once a user has removed a finger from the button. In this way, air is returned from the inlet/outlet port into the bellows. The primary disadvantage with the bellows system is that the bellows themselves need to be constructed from a flexible material which will inevitably wear as a result of flexing in use. For example, the material which is most commonly used is a rubber or plastics material and such materials ultimately fatigue and perish so that air escapes from the bellows.
It is an object of the present invention to provide a pneumatic switch operator which will at least go some way toward overcoming the foregoing disadvantages, or which will at least provide the public with a useful choice.
The invention consists of a pneumatic operator including a plunger having an end wall and one or more side walls defining a space therebetween and a button surface for application of a force by a user in use to displace the plunger, an inner body provided in use within the one or more side walls, sealing means provided between the side walls and the inner body, and an air inlet/outlet port provided in the inner body or the plunger, the arrangement and construction being to allow the plunger to move relative to the inner body whereby movement of the inner body into the plunger expels air from the space out of the inlet/outlet port.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as claimed herein. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.